Modular-value-based metrology with spin coherent pointers

TL;DR

This paper explores the use of modular values in quantum metrology with spin coherent pointers, demonstrating enhanced sensitivity in higher-dimensional systems and analyzing the impact of phase-flip errors.

Contribution

It introduces a modular-value-based measurement scheme with spin coherent pointers and evaluates its effectiveness in different dimensional systems for quantum field estimation.

Findings

No advantage in 2D pointers.

Enhanced sensitivity in higher-dimensional pointers.

Impact of phase-flip errors analyzed.

Abstract

Modular values are quantities that described by pre- and postselected states of quantum systems like weak values but are different from them: The associated interaction is not necessary to be weak. We discuss an optimal modular-value-based measurement with a spin coherent pointer: A quantum system is exposed to a field in which strength is to be estimated through its modular value. We consider two cases, with a two-dimensional and a higher-dimensional pointer, and evaluate the quantum Fisher information. The modular-value-based measurement has no merit in the former case, while its sensitivity can be enhanced in the latter case. We also consider the pointer under a phase-flip error. Our study should motivate researchers to apply the modular-value-based measurements for quantum metrology.